Smelting process and apparatus therefor.



R. FLEMING. SMELTING PROCESS AND APPARATUS THEREFOR. APPLICATION FILED JULY 13. 1909.

981,850. Patented Jan. 17,1911.

2 SHEETS-SHEET 1.

R. FLEMING. SMELTING PROCESS AND APPARATUS THEREFOR.

I APPLICATION FILED JULY 13. 1909. 9 1,350, Patented Jan.17, 1911.

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E 5 Q A 'nuentop wmm wgd wi-wmz UNITED STATES- PATENT OFFICE.

RICHARD FLEMING, OF NEW ROCHELLE, NEW YORK.

smnmrne rnoonss AND AIV'PARATUS THEREFOR.

Specification of Lettersl'atent. Y

. To all whom it may concern:

. mg the gravital separation of such liquefied- Be it known that; I, RICHARDFLEMING, a citizen of the United States, residing at 23 Euclid Place, New Rochelle, in the county of Vestohester and; State of Newliorlnhave invented certain n'ewand useful Improvements in Smelting Processes and Apparatus Therefor, of; which the following is ;a specification.

i This invention .relates to smelting processes and apparatus therefor; and it comprises a method of concentratingores by 11- quating valuable metalliferous minerals therefrom with the aid of a layer'of matte maintained in a molten condition and electri cally heated, the liquated mattersbeing then separated from the valuel'ess constituents of said ores; and; it also comprises certain apparatus, or organizations of apparatus. elements, useful in performing said process, said apparatus comprising a vertical inclosed chamber adapted to maintain a layer of molten matte and mineral matter upon its hearth and a column of mineralized matter means for electrically or ore thereabove', heating said matte iug volatilized and electrically heated layer, means for removliquefied matters and an forehearth for perfectmatters; all asniore fully hereinafter set forth and as claimed.

In extracting copper and other-valuable metals from their ores one of themethods customarily employed is the conversion of the valuable minerals into matte. Matte. is

a more or less indefinite mixture of sulfids and other bodies; copper matte being a mix ture of cuproussulfid, or copper subsulfid (Gu S) with other sulfids, arsenids, antimonids, etc. Ordinary'copper sulfid (CuS) upon heating loses half its sulfnr and becomes converted into the subsulfid. Pyrites (F e3 similarly, upon-heating loses half its sulfur as such-by volatilization andbecomes converted into ferrous sulfid (FeS). These two lower sulfids form the main part of the ordinary mat-tes; copper matte, for

example, being ordinarily a mixture of cuprous and ferrous sulfids with indefinite amounts of other sulfids, of antimonids or arsenids, and, perhaps, of various oxids. Little is definitely known as to the'form in which gold,'silver, nickelycobalt and other valuable metals occurin the ordinary mattes. I

Matte has many valuable characteristics for metallurgicalpurposes since it readily dissolves most of to be a loss of copper,

the copper oxidizing under the oxidizing conditions usually slag oil with the silica ores. In the presence of fid however copper and metals do not so tend to slag away; and for this reason itis customary to cause the matte to contain considerable ferrous sulfid.

In the production of copper matte, many methods are in use. the ore in a reverberatory furnace, burning ofi' the'excess of sulfids overthat necessary to make the desired matte and slagging off the silica, silicates, etc., always present in ore. Often. the'greater part of the sulfids are first destroyed by roasting the ore in var1ous'ways; a 'processlwhich is disadvantageous since the heat produced in the oxidation of such sulfids cannot well be utilized in thesmelting operation proper and since the roasting converts the iron largelyinto the highly oxidized form of F e 0 which always present in suflicient' iron sulmatte making operation. Another method seeks toutilize the heating value of the sulfids by burning the ore with air blasted through a massthereof in a converter or in a shaft furnace; the latter being the method usually done with raw ores. This burning however can practically only be employed with ores consisting mainly of iron pyrites (Fes Pyrites under these conditions first and this latter then oxidizes, the iron oxidizing to F eO which slags ofl with the silica present and the sulfur burning to $0 which escapes as a gas. Both these oxidations yield heat as .does the oxidation of the liberated'atom of sulfur. The conditions in the ordinaryshaft furnace are not well suited however to burning this liberated; sulfur 7 since it escapes upward from the molten mass around the twyers and condenses in the atented Jan. 17, 1911'. Application filed July 13, 1909. Serial No. 507,354. 3

One is simply to smelt:

must subsequently be again reducedfin-the.

maintained in matte making and tending to 1 the other valuable.

loses one atom of. sulfur by volatilization and combustion, becoming converted into F eS,

the valuable metalliferous minerals and native metals, and when produced in ores containing copper, gold, silver, nickel and cobalt it readily dissolves In ordinary matte makit is rarely allowed since with higher percentages there is apt ore mass above. Neverthelessfin smelting rich pyritous ores in a shaft furnace the heat evolved in burning a modicum of the charge (a portion of the sulfids inust be left unburned to produce matte) may be sufficient to fuse and slag off gangue (the ferrous oxid formed acting as a'very eflicient flux for this purpose) and give a fused mass of matte containing substantially all the gold, silver,

copper, nickel and cobalt of the charge. Unfortunately the richer ores are rarely pure sulfids and with manyores the heat evolved in simple oxidation of the sulfids present is insufficient to effect the desired results. Furthermore, there'is not always sufiicient iron pyrites present to afford the desired amount of heat by its combustion and also to afford sufficient ferrous sulfid to shield the copper, etc., in the matte while the addition of pyrites to the ore under treatment is not always practicable, and, if the pyrites available happens to be a barren type, the addition of this material to the charge involves expense and labor without'concomitant results. Poor ores are therefore often first concentrated by the ordinary metallurgical methods, as by wet concentration, to remove the bulk of the gangue and waste mineralmatter and leave a mass of comparatively pure and rich sulfids for the matte making treatment, but this not only involves expense and loss, but the fines recovered are not in good physical condition for handling in the ordinary matte smelting devices, such as shaft furnaces, converters and the like, the fine ore dusting away and i also impeding the draft. In any ore, a large proportion will be found to exist as fines and these fines, like those resulting from concentration, are diflicult to handle, while such fines are frequently the richest portions of the ore. In practice, it is foundthat in these oxidation methods when employing ordinary ores or concentrates and smelting in a shaft furnace it is usually necessary to add more or less carbonaceous fuel, such as coke, to the charge to furnish more heat units. But

fuel is not only usuallyexpensive in the dis-,

tricts where metalliferous minerals are found but its use in conjunction with matte smelting introduces many complications. In

smelting sulfids to form matte in the mancopper matte, avoiding the noted objections and securing many new advantages while being applicable to many ores which cannot now be easily orcheaply treated. To this Cu S, etc.

end, I first produce a layeriform body or bath of molten sulfids or matte, maintaining it in the molten condition by the supply of external energy. Most conveniently, this energy is supplied by electrical heating, either resistance heating or inductive heating as may be desired. Molten mattes are well adapted for resistance heating as they are conductive .for the current. The current employed is preferably alternatingto avoid complicating the reactions by electrolysis. In the embodiment of my invention at pres ent preferred no electrolysis is desired. The voltage and amperage employed will of course depend upon the mass of conductor,

the length of conductor employed and the temperature desired.

Preferably the bath of matte is given the form of a long shallow narrow pool maintained upon the hearth of a similar and inclosing chamber, such chamber being, if desired, of greater cross-sectional area than the column of ore to be supplied to such pool.

\Vith the aid of this inclo'sing chamber, very exact conditions of temperature and oxidation maybe maintained. The heat of the matte does not escape and the conditions as regards heat and as regards oxidation may be maintained as desired. If so desired, no oxidation whatever may occur or any controlled amount of oxidation may be effected. Where oxidation is effected, the electrically developed heat may also be used to complement it.

Sulfids delivered to this molten pool will be melted and, where containing more sulfur than corresponds to the matte-making sulfids, will be freed of the excess of sulfur by volatilization; FeS for instance, becoming FeS with liberation of S; @118 becoming \Vhere oxidized ores or metals are used together with the sulfid ore or where the ore itself contains oxids, such as CuO, carbonates, such as copper carbonate, etc., this excess of sulfur functions usefully in, converting such bodies into matte also.

\Vith ores containingan excess of sulfur over'that needed for matte-making, this excess may also be caused to function usefully in anotherway hereinafter setforth.

comparatively cold, solid sulfids delivered"into the bath of hot molten matte in the path of the current cause a local rise in resistance and a consequent'local development'of heat until such sulfids are melted.

In the embodiment of this process at present preferred, therefore, after the production of an electrically heated, linear pool of molten matte, the ore to be-treated is de livered into it between the electrodes; preferably asone or more heaps or columns having one or more free sides and coming. from corresponding hoppers, and bases resting in the bath of matte with molten matte on either side in the path ofhaving their the current; Such a heap'niay be caused to assume the shape of an angle-of-repose pile of the cross-section oftthe fluid conductor in aking processes.

where they occur and also by the chilling,

Witha consequentlocal development of high temperature in such base at these points, of the ore quickly melting the solid sulfids and liquating themout of the gangue to join the body of molten matte. -The molten matte is allowed to flow away from the pool as the latter exceeds its predetermined level,

thereby maintaining 'the depth and resistance of the pool approximately constant.

And with such an angle of repose pile rest' ing at its base in the pool of molten matte, the unmelted ore at Its base is positively held within. the molten layer and does not float. e 1 1 \Vhile in the present embodiment of this invention it is preferred to have'the ore piles resting in the matte pools of less cross-sectional area than such pool or the chamber itself, as in feeding the ore in piles having an anglcofrepose on one or more sides, yet the ore column may substantially fill the chamber above the matte pool; and particularly Where a smelting operation is resorted to in addition to the electrical heating;

The particular "state of comminution of very important in process at present preferred, fines having no opportunity to impede draft or to dust away while, onthe otherhand, if the ore be employed in a coarse state, the sudden heating ,as it con- 'tacts with the molten matte tends to crack and shatter it -in a way permitting efiicient' liquation of the contained sulfids. Fine ore and concentrates are however preferred as Working more uniformly. 1

In the process as just described, there be ing no oxidation necessarily required there,

need be no excess of sulfids to produce a matte, it being suflicient if enough sulfur be 1 prescntto form matte with the valuable metals of the ore. Nor'is anexcess of ferrous sulfid necessary in the matte, to shield the copper. Chalcocitc, or copper glance, for instance,'may be liquated out of ore to form a pure copper matte without the necessity forwthe additionofother sulfids to shield the cuprous subsulfid of this ore. Thesame is true of ores containing only such sulfids as chalcopyrite (CUFeS bornite (Cu FeS etc. Ores of this character cannot of course be used without other sulfids in ordinary pyritic smelting or in other, ordinary matte Oxidized ores may with sulfu'reted ores, it

being necessary to be used in conjunction ,etc.

The described process ishowever also applicable to richer sulfid ores and concentrates, such as pyrites or mixtures containeconomies and advantages may be obtained by the use of certain expedients. For in- --stance, the sulfur vapors freed in heating the molten matte may be ledinto suitable collecting chambers and condensed as flowers of sulfur as in my No. 439,521 (Patent 945,926, Jan. 11,1910).

the recovery of such vapors as may also sweeping currents of neutral gases, like products of combustion,, steam, etc. For this recovery, it is better that the ore be con tained in a comparatively large chamber, leaving a free space about the pile for the reception of the vapors since sulfur vapors accumulating within the ore pile are not readily "withdrawn without the use of an undue amount of draft. The use of the described angle-of-repose piles for this purpose is convenient. A free surface vof the matte pool is'also desirable. Another method of securing utility from these evolved sulfur vapors is to introduce air in limited amounts intothe chamber above the matte bath, causing the evolved s'ulfur to burn in or about the ore piles, yielding heat-thereto and economizing in'the amount of heat to be developed in the bath proper. When so burned, not only is the heat utilized but richbodies of gases are formed which may beemployed for making sulfuric acid, sulfur trioxid, etc.

en air is used for burning free sulfur, the sulfur dioxid formed is diluted only by the nitrogen accompanying the oxygen uniting with the sulfur while when burning pyrites the gas mixture produced is diluted also by the nitrogen accompanying the oxygen fixed by the iron as iron oxid. The sulfurous vapors formed in the ordinary-matte-makare not nearly "so advantageous for acid making. With such ores rich 1n sulfur. development of heatcan also,1f desired, be

the pool and giving heat to reinforce-that electrically developed. This is particularly useful in treating ores containing much fluxing agent;

With such ores rich in sulfur, by a modi- Lake Superior or Arizona copper, gold in quartzfscrap copper, mattes, concentrates,

copending application D raft means may be employed to facilitate caused to occur in the bath of matte itself,-

a certainamount of air being blown through ing pyrites, and in such application many ing processes are of this latter character and 1 silica or silicates since oxidation insth e matte bath forms oxld of iron which is an. efliclent' fication of the present invention an improved type of pyritic smelting may be 'produced, a shaft chamber, preferably long,

narrow and comparatively high adapted to contain a descending column of ore being provided with the described type of hearth adapted to form and maintain a shallow linear pool of electrically heated molten matte and being also provided with twyers for introducing air into such pool. In the ordinary type of pyritic smelting, it is usually necessary in practice to supplement the heat developed by the oxidation of the sulfids by heat developed by the oxidation of carbon; or, in other words, to feed-more" or less cabonaceous fuel with the ore charge. This carbon, as stated, complicates the conditions within the furnace, not only by using up a portion of the air but by developheat which need be furnished by the ourrent is minimal, theoxidation by thedraft itself furnishing nearly all the required heat units. \Vith a controllable; supply of electrically generated heat, the reactions within the smelting chamber becomes also controllable and the whole smeltin 'o ration is rendered positive and contrcflable stated modification therefore, a shaft furnace is supplied with a descending column of ore or ore mixturesin the usual way, the basal pool of molten' matte and slag being maintained in a molten'condition and tappe ofi in the usual way while a blast of air, heated or unheated, is supplied at the base of the column, being blown through the matte pool or immediately thereabove as may be desired.

to supplement that developed by the oxidation and-to even out temporary irregularities.

therein is supplied to thematte by electrical energy in the manner described.- VVhile if desired for any reason a limited amount of carbonaceous fuel, such as wood, coal'or coke, may be supplied to and admixed with the ore charge, this is not ordinarily desirable or necessary, the heat of oxidation of the sulfids and the electrically developed A heat in reciprocallyproportioned amounts being relied upon to establish the necessary thermal and other conditions within the shaft chamber. I The useof an inclosing chamber makes it practicable to employ direct heating of the slag produced ma In, thethe treatment A suitable amount of heat shown,

the ore pile resting at its base in the molten matte as by the use of flames of burning1 oil, gas, etc., which are made to play on the cap or heaps of ore where these are spaced away at one or 'more points from the wall of the containing chamber to aid in preheating; or upon the matte bath itself. In doing the latter, the floating slag serves to protect the underlying matte from the direct action of the flame and preclude undesirable reactions. The ore may of course be pre heated before introduction into the apparatus, as may air blasts when used.

The gangue occurring with or in the ore :may be slagged or not, as may be desired,

or as circumstances may dictate. Ordinarily it is better to slag it, at least in part, thoug contain comparatively large grains of si ica or silicates without loss, in many instances. Many ores are so constituted that a simple liquation yields all'the values under the circumstances described. If the ore be not self-fluxing, fluxing ores or substances may of course be added, or oxids of iron, etc., may be produoed therein as described. In burning the sulfur in or around ore heaps in the manner described, a limited oxidation of the ore itself may be permitted; or oxids may be formed by blasting. the matte with limited amounts of air. As will be obvious, the described method permits a wide range of variations in treatmg various .ores and -1 I'l slagging the gangue. Since the electrically developed heat in the matte bath .is independent of the composition of the one or char e, the temperature may be as highas may desired and any type of slag may be used, whether low.melting or not.

With many ores, and particularly where comarati velyviscous or infusible-slags are pro uced, I find it desirable to supplement in the chamber described by the use of an electrically heated forehearth.

With a shallow, comparatively small bath of .molten mattes, the opportunities for gravital separation may not be as good as esired.- Itherefo're customarily draw off the overflowing slag and matte into such a forehearth this being of comparatively large dimensions to give a good opportunity for settling. An e cient way of roducingheat in this forehearth at the .pomt where it is desired is to. a proximate a pair of electrodes 'connecte to a sourw of alternating current to the floating layer of slag. The resulting arcs and the resistance of the sla will raise it to any'temperature desired an cause it to .be fluid enough to quickly drop included prills of matte. It is desirable that the electrodes should not reachto the underlying matte layerg.

In the accompanying illustration I haye more or lws diagrammatically, eel.

tain. organizations of apparatus elements within the scope of this invention.'

In this showing, Figure 1 is a vertical longitudinal sectionof a smelting apparatus,

the view being taken along line y-y of Fig. 2; Fig. 2 is a vertical transverse section of the same apparatus, the view being taken along line 00-02 of Fig. 1; and Fig. 3 is a Vertical transverse section alongline z-z, of Flg. 1, showing the forehearth. Referring first more particularly to Fig. 1, a long shaft chamber 1, having walls 2 of refractory material suitably supported by spaced metal reinforcing elements 3 shown as Water cooled (said reinforcements being so arranged as not to form a continuous electrical conductor and give rise'to short circuiting) is provided with a series of hoppers 4, closed by gates ,5, and so positioned as to afford a similar series of piles ofore 6, resting on the hearth T in an angle-of-repose position, their bases being bathed by the pool of matte 8 and super-incumbent slag layer 9. Passing troughthe chamber .25 walls or (as shown) through the hearth at each end is an electrode 10, the two electrodes being connected to a source of suitable alternatingcurrent 11. These electrodes may be made of in ot copper or steel 3 castings and are preferabf ,as shown, watercooled. Passing through one end of the chamber is an outlet conduit 12 which may be connected to a sulfur chamber (not shown) or to any other device for utilizing fumes of sulfur or sulfur dioxid. Through the opposite wall passes an air conduit 13, gated at 14, and connected to any suitable source of air. or other gases, asfan 15. Below this air conduit is another aperture 16 through the chamber wall, closable as by door 17, through which, if desired, a current of flame may be sent by firing device 18,

shown as an oil burner. Outlet 19 serves to remove matte and slag and to keep the liquid level on the hearth constant or approximately so. Twyers 20' (see ig. 2) are so arranged as to render it possible to blow air through the pool of matte'upon the I hearth while the upper pair of twyers 21at a higher'level allow introducing air or flame on the surface of the'liquid pool.

Referring more particularly to Fig. 3, the matte outlet 19 of the chamber is shown as communicating by conduit 22 with forehearth 23. This forehearth is shown as a chamber large enough to con-' talnan accumulation of matte and slag and suitably roofed at 24. Slag outlet 25 and matte outlet 26 at different levels respectively permit removal of slag and matte from time to time or continuously. Through the roof of the forehearth pass a pair of'electrodes 27, connected to an suit-. able source of current,.whic'h is pre erably alternating and in arc-producing relationship to the slag layer.

In the use of the described process with the described apparatus, the hearth is first supplied with molten. matte from any suitable source and a suitable current is passed through the layer, which forms a resister, to maintain it at any desired temperature. Supposing apoor ore, containing merely enough sulfur to matte the valuables, is to be treated, this ore, mixed if-neeessary with sufficient flux or fluxing ore to slag the gangue or the major part of it (and. the slag produced need not necessarily be of a type which is particularly fluid under ordinary conditions since the electrical heating in the furnace and in the forehearth will give any temperature desired) of-repose piles on the hearth, resting in the pool of matte. WVherever these piles occur, the resistance of theconductor is raised and more heat is developed; or, in other words, heat is developed where the ore is wetted by the matte. This heat melts and liquates out any sulfids present and converts them into matte. VVithore and matte protected is passed into the chamber from the hoppers, forming angleand shielded by the inclosing chamber there need be no more sulfur in the ore'than is necessary to form the matte, it not being necessary to rely upon the combustion of sulfids for the heat. With ores richer in sulfur, any excess of sulfur present beyond that necessary to form FeS with the iron and Cu. ,S with the copper, will distil up into the chamber whence it. may pass away through outlet 12. Arsenic, antimony and other metals volatile under the particular conditions employed 'may also pass forward with the sulfur vapors. The whole chamber being hot, the sulfur dqes not condense on thewalls and that condensing in the 'sinking pile ofore is 'again evaporated. The operation being performed m a closed chamber. an accurate control of thermaland other conditions, is possible. Under the high heat of the matte bath, the parti; clcs of ore crack and shatter, allowing the molten sulfids to liquate out and join the matte while the slagged ga'ngue rests on the matte. It is not very lmportant here when using thedescribed'type of forehearth, whether the separation of matte from the slag be very good or not. Slag and mat-te pass together intothe forehearth and separate gravitally. The slag beingheated and liquefied by current from poles 27, 1t drops any inclosed prills of matte."

If the ore be rich in sulfids, as where 1t contains considerable pyrit'es, the dlstill ng sulfur coming from thematte bathmay be burned in or around the piles of ore by air from 13, ielding up its heat to warm the ore and furnishing rich fumes of ;sulfur dioxid at outlet 12. Further heat may also be furnished in the bath itself by twyers 20 supplying air to burn a portion of the iron sulfid to form ferrous oxid, which will aid in slagging any silicious gangue, and to add heat to the bath of matte. c

As stated, the heat developed by oxidation'may be the main part of that developed within the chamber, the electrically devel- 10 oped heat being used merely as a supplementary and compensating means.

With ores rich in pyrites when oxidizing the matte on the hearth it is often advisable to use an admixture of a silicious ore, either a copper ore or an ore bearing another valuable metal, such as gold-bearing quartz.

With poor ores, containing but little sulfid,

for the sake of economy of heat in producing the desired temperatures, a jet of flame may be introduced through 16, playing on the piles, or flame may be introduced through 21 and directed on the surface of the slag covering the matte layer. a

The matte passing from the forehearth 25 may be treated in any of the usual ways, as

.by blasting in a-Manhes converter, treatment 1n a reverberatory, etc., to recover copper and'other values therefrom.

The hearth may be, as shown, somewhat- V-shaped in section.

The electrodes are preferably rather massive and are water cooled. The series of casings 'inclosing and supporting the refractory walls of the furnace, should be, as shown, spaced away from each other somewhat to prevent shortcircuiting'between the ends of the furnace, and for the same reason they should be provided with individual means for water cooling. If they are connected to a common water-supply or waste outlet by all-metal piping, short circuitin can, of course, occur, and for this reason ru her or other non-conductive tubing should be provided as part of the supply and-waste means for each. of

i the individual jackets.

That I claim is 1. The process of smelting ores which comprises forming and maintaining a comparatively long and narrow layer of molten matte in an inclosed chamber under controlled conditions ofheat and oxidation while feeding ore comprising sulfur and copper current longitudinally through said layer r and feeding ore comprising sulfur and copper to such molten layer, said ore being fed as a body lying in the path of such current.

3. The process of smelting ores which comprises forming and maintaining a comparatively long and narrow layer of molten matte in an inclosed chamber under controlled conditions of heat and oxidation, maintaining suchlayer in a molten condition with the aid of heating current transmitted longitudinally therethrough and feeding ore comprising sulfur and copper to such molten layer, said ore being fed as a body lying in the path of such current and said body extending upward above the level of such layer.

1. The process of smelting ores which comprises forming a layer of molten matte in a suitable inclosed chamber under the controlled conditions of heat and oxidation, maintaining such layer'in' a molten condition with the aid of heating current longitudinally transmitted therethrough and feeding ore comprising sulfur and copper to such molten. layer, said ore being fed as a body lying in-the path of such current and said body extending upward above the level of such layer and having a side out of contact with the chamber wall.

5. The process of smelting ores which comprises forming a layer of molten matte in a suitable chamber, maintaining such layer in a molten condition with the aid of heating current longitudinally transmitted therethrough and feeding ore comprising sulfur and copper to such molten layer, said ore being fed as a body lying in the path of such current and said body extending upward above the level of such layer, and having a side out of contact with the chamber wall, sulfur volatilized from such layer being burned about the extended portion to heat the same.

6. The. process of smelting ores which comprises maintaining a comparatively long and narrow layer of electrically heated molten matte in an inclosed chamber under controlled conditions of heat and oxidation, while continuously feeding heated ores comprising sulfur thereto and removing molten matte and slag therefrom.

7. The process of smelting ores which comprises maintaining a comparatively long and narrow layer of electrically heated molten matte in an inclosed chamber under controlled conditions of heat and oxidation while continuously feeding heated ores comprising sulfur and copper thereto and remoyingmolten matte and slag therefrom, said layer having other heat supplied thereto.

8. The process of smelting ores which comprises maintaining a comparatively long and narrow layer of electrlcally heated molten matte in an inclosed chamber under controlled conditions of heat and oxidat on while continuously feeding ores comprising sulfur thereto and removing molten matte and slag therefrom, a portlon of air being introduced into said layer to aid in heating and to furnish slag-forming oxids andvsaid layer having heat electrically supplied thereto.

9. The process of smelting ores whicli comprises producing and maintaining a layer of molten matte having heat electrically supplied thereto, feeding ore into such la ver in angle -ofrepose piles extending thereabove and having a free side, burning volatilized sulfur about the upper extension of the ore piles and introducing a modicum of air into such layer to aid in heating and to furnish slag-forming oxids, drawing ofi' molten matte and slag into a forehearth for gravital separation and during such separation electrically supplying heat to the slag layer.

10. A smelting apparatus comprising a closed chamber having a long and narrow shallow hearth and provided with an overflow outlet spaced thereabove sufficiently far to allow the formation of a shallow pool of molten matte, means for passing alternating current through the molten pool on such hearth, means for feeding sulfidtore to the molten material upon such hearth and means for utilizingsulfur volatilized from such molten material.

11. A smelting apparatus comprising an inclosed chamber having a comparatively long andnarrow shallow hearth, one of the chamber walls being provided with an overflow outlet spaced above the hearth suffi ciently far to allow the formation of a shallow pool of molten matte, means for passing alternating current through the molten pool on the hearth, and means for feedin sulfid ore upon such hearth 'in angle-of repose piles.

12. A smelting apparatus comprising a closed chamber having a long and narrow shallow hearth, one of the chamber walls being provided with an overflow outlet spaced above the hearth, means for passing alternating current through molten material on the hearth, means for feeding sulfid ore upon such hearth in angle-of-repose piles, and means for burning volatilized sulfur around such piles.

13. A smelting apparatus comprising a chamber having a shallow hearth and having certain walls spaced apart farther than the widtlr of said hearth, betweenv other walls, one of said walls being provided with an overflow outlet spaced above the hearth, means for passing alternating current through molten material on the hearth, means for feeding sulfid ore upon such .hearth in angle-of-repose piles, means for burfiing volatilized sulfur around such piles and means for introducing a modicum 0 air into the molten material upon said hearth.

14. In combination, means for producing a constantly replenished comparatively long and narrow electrically heated molten layer of matte and slag in an inclosed chamber and means for, withdrawing produced matte and slag for gravital separation, the last named means comprising means for electrically heating the layer of separated slag.

15. A matte producing apparatus comprising a smelting furnace provided with an inclosed chamber having a comparatively long and narrow and shallow hearth and having an overflow outlet spaced thereabove, means for passing an alternating current through molten material on said hearth, means for feeding sulfid ores to said molten material, a forehearth withdrawing molten matte and slag through said outlet and means for electrically heating the layer of slag in said forehearth.

having walls of refractory materials and having a hearth, electrodes at each end of said heart-h passing through said walls and a plurality of exterior reinforcing metal casings supporting said walls intermediate said electrodes, such casings being spaced away from each other and each such casing beingprovided with individual means for water cooling the same.

17. In combination, a vertical chamber having walls of refractory materials and having a hearth, electrodesnt each end of said hearth, each such electrode being pro vided with means for water cooling the same, and a plurality of exterior reinforcing metal casings supporting said walls intermediate such electrodes, such casings being spaced away from each other and each such casing being provided with individual means for water-cooling the same.

18. The process of smelting sulfid ores which comprises producing and maintaining an "electrically heated comparatively long and narrow layer of fused sulfids in an inclosed chamber, producing and maintaining a pile of ore with its base resting in such layer in the path of the current and having a free side within such chamber and heating such side by combustion heat. v

19. The process of smelting sulfid ores which comprises producing and maintaining an electrically heated comparatively long and narrow layer of fused sulfids 1n an inclosed chamber, producing and maintainin a pile of ore with its base restlng in such layer in the 'ath of the current and having a free side within such chamber and heating such side by combustion of extricated sulfur.

20. The process of smelting sulfid ores which comprises producing and maintaining an electrically. heated comparatively long and narrow layer of fused sulfids 1n an inclosed chamber, producing and maintaining a pile of yore with its base resting, in such layer in the path of the current and having a free side within such chamber, producing oxidation within such layer by air blown therethrough and heating such side by combustion heat 21. The process of making copper matte which comprises producing and maintaining an electrically heated comparatively long. and narrow layer of copper mattein an inclosecl chamber, producing and maintaining a comparatively tall column or pile of ore comprising sulfur and copper within such chamber with its base resting in such layer in the path of the current, such pile 15 having a free side, heating such side by combustion heat and producing oxidation within such layer by blowing air therethrough.

In testimony whereof; I. afii'x my signa- 20 ture in the presence of witnesses.

RICHARD FLEMINGL Vitnesses K. P. MoELRoY, y H. O. CHUTE, 

